This invention relates to new and useful improvements in fluid current motors for harnessing the energy of natural currents, and more particularly to a fixed water motor installation for transforming the energy of flowing tidal currents and the like into a useable rotational force and for storing any excess energy generated by the motor.
Fluid current motors have long been known in the art and are exemplified by the devices disclosed in U.S. Pat. Nos. 15,970; 34,600; 113,586; and 863,033. Such devices typically employ a plurality of horizontally pivotable blades or buckets suspended from a wheel-like frame which is rotatably mounted about a vertical axis. The frame is positioned so that the blades are substantially submerged to a predetermined depth below a given water level. The blades are provided on one side thereof with stops to resist the pivoting force exerted by the water current in one direction to thus maintain the blades in a vertical position. The reaction of the flowing current on the vertical planar surface of the blades produces rotation of the motor frame thereby converting the kinetic energy of the flowing current to rotational energy. Upon rotation of the frame to expose the other side of the blade to the current, the blades are free to pivot and, under the force of the current, eventually assume a substantially horizontal or "feathered" position to minimize resistance to the flow of water thereover.
Vertical adjustment of blade depth according to the level of the flowing water current is provided in the fluid motor disclosed in U.S. Pat. No. 34,600 by means of a chain which is used to manually raise and lower an adjustable hub upon which the blades are supported.
In general, the fluid motors of the aforementioned prior art devices are provided with pivotable blades of substantially planar construction, or, as shown in U.S. Pat. No. 863,033, they may have forwardly curved edges to form bucket-like members. Each of the blades or buckets of the prior art devices must present a reaction surface area on the opposite side of the blade to the flow of current so as to actuate the pivoting of the blade from its vertical or operative position to its feathered or inoperative position and vice versa. The force required to cause such pivoting produces a significant rotational force counter to the normal direction of rotation of the fluid motor and, consequently, reduces the fluid motor efficiency.